Passivation of semiconductor surfaces with low-energy hydrogen

在这项工作中，我们研究了热或远程等离子体激发氢诱导的表面反应及其对硅相关半导体表面电结构的影响。首先，我们尝试在低衬底温度下通过原子氢（或氘）暴露去除硅上的氟吸附物。通过原位俄歇电子分析发现，在200℃的温度下，氟吸附物被完全去除。此外，我们通过热激脱附光谱（TDS）证实了氢钝化表面。在除氟过程中，我们估计初始阶段的主要反应产物是SiD2F2分子，而SiDF分子是降低氟原子表面密度的分子。其次，我们用等离子体激发氢在低于350ºC的WF6气体中在Si和SiO2衬底上沉积了钨薄膜。随着激发氢供给的增加，钨膜的非选择性生长，反应顺序发生改变，沉积膜的电阻率降低。这些现象是由于氟原子从WF6及其表面的萃取活化所致。第三，研究了加氢对未掺杂多晶硅薄膜电特性的影响。我们提出了一个电流传导模型，既包括传统的带式导电元件，也包括沿晶界的跳变导电元件。该模型可以解释氢化引起的薄膜电阻率和活化能的变化趋势。

In this work, we have investigated on thermally or remote plasma excited hydrogen induced surface reaction and effects on a surface electric structure of silicon related semiconductors.First, we tried to remove fluorine adsorbates on silicon by atomic hydrogen (or deuterium) exposure at low substrate temperature. From in-situ Auger electron analysis, it is found that the fluorine adsorbates are completely removed at 200ﾟC through this process. Moreover, we confirmed the hydrogen passivated surface from TDS (thermally stimulated desorption spectroscopy). During the fluorine removal process, we have estimated the SiD2F2 molecules as main reaction products in the initial stage , and the SiDF molecules as those decreasing the surface density of the fluorine atoms.Second, we have deposited tungsten films onto Si and SiO2 substrates from WF6 gas with plasma excited hydrogen below 350ﾟC.Increasing the supply of the excited hydrogen, the tungsten films grow non-selectively, the reaction order changes, and the resistivity of the deposited films decreases. These phenomena are due to the activation of the extraction of fluorine atoms from WF6 and the surfaces.Third, the effects of hydrogenation on the electric characteristics of undoped polycrystalline silicon films have been investigated. We propose a current conduction model including both a conventional band conductive component and a hopping conductive component along the grain boundary. This model can explain the tendency of the variation of the resistivity of the films and its activation energy induced by the hydrogenation.